frontend-plugin-api: accept IconElement in AuthProviderInfo

Update the `icon` field on `AuthProviderInfo` to accept `IconElement`
in addition to `IconComponent`, and update consumers in core-components
and user-settings to handle both types at runtime.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

.changeset/auth-provider-icon-element-core-components.md

@@ -0,0 +1,5 @@
+---
+'@backstage/core-components': patch
+---
+
+The login request dialog now handles auth provider icons passed as `IconElement` in addition to `IconComponent`.

.changeset/auth-provider-icon-element-user-settings.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-user-settings': patch
+---
+
+The `ProviderSettingsItem` `icon` prop now accepts `IconElement` in addition to `IconComponent`.

.changeset/auth-provider-icon-element.md

@@ -0,0 +1,5 @@
+---
+'@backstage/frontend-plugin-api': patch
+---
+
+The `icon` field on `AuthProviderInfo` now accepts `IconElement` in addition to `IconComponent`, letting you pass `<MyIcon />` instead of `MyIcon`.